1. Field of the Invention
The present invention relates generally to agricultural seeders that make furrows in the soil into which seeds are placed, and more particularly, to an improved seed tube mounting assembly for use with such seeders.
2. Description of the Related Art
Agricultural planting methods continue to advance in response to widespread adoption of “no-till” or “reduced-till” crop production techniques with greatly reduced dependence on tillage of the soil, and in which the next crop's seeds are often placed directly into the previous crop's stubble or crop residues. No-till or reduced-till seeding differs greatly from seeding into a tilled seedbed. Although the soil conditions for no-till seeding are typically characterized by more structural stability than tilled soils, as the soil particles are “aggregated” or held together by old roots, fungi, and other organic substances and molecular attractions binding the particles together, it is still of considerable importance to prevent loose soil and “duff” (chaff and small pieces of partially decomposed mulch) from entering the seed furrow prematurely, before the seeds have come to rest at the bottom of the furrow. This is of particular importance on single-disc opener designs which are particularly vulnerable to loose soil and duff sloughing into the furrow after the opener disc has passed, relying on soil stability and/or a seed boot to inhibit the loose soil and duff from entering the furrow until after the seeds have been adequately placed in the bottom of the cut furrow.
Single-disc opener designs for seed or fertilizer placement have met with considerable success in no-till seeding, partly due to simplicity. Because of the structural stability of no-till soils, much higher down-force requirements are imposed on the opener disc to cut the furrow to a consistent depth. This additional strain generally necessitates more robust opener discs together with a much larger hub and mechanical bearing(s) on which the opener discs are rotatably mounted, and this durability requirement also lends an advantage to the single-disc design for cost and space constraints. Larger hubs and bearings on the opener discs can interfere with the routing of seed-delivery tubes and positioning of gauge wheels.
Gauge wheels pose a design problem because the most desirable positioning is with the gauge wheel contacting the soil most forcefully at the point where the opener disc's rearward edge is rotating up out of the soil. This allows the gauge wheel to control “sidewall blowout,” which results from the opener disc's upward rotation and angle to the direction of travel causing the furrow sidewall to tear apart and lift upward, i.e., following the disc's rotation upward as it exits the furrow. When left unchecked, sidewall blowout sometimes results in the furrow sidewall tearing completely free and being flung out of the furrow by the opener disc's momentum, thereby creating an irregularly shaped furrow and/or allowing pieces of the sidewall to enter the furrow before seeds have been properly placed.
The opener disc is typically mounted at a slight angle to the direction of travel so that it is pushing soil laterally to create a furrow. For controlling sidewall blowout, gauge wheels generally are mounted in the same plane as the opener discs, with the inner lip of the gauge wheel flush against the outer edge of the opener disc (“outer” refers to the side away from the furrow being cut). With a 16-inch or 18-inch diameter opener disc (the preferred disc sizes due to optimal cutting ability at 1.5- to 2-inch seeding depth; larger sizes hairpin more mulch, and smaller sizes are more prone to plugging or “bulldozing” of clumps of straw or debris), and a 15-inch gauge wheel (again, the preferred size, since smaller sizes resist rolling over small obstacles in the field, and larger sizes get in the way of other components), the forward edge of the gauge wheel is then approximately at the axis of the opener disc, which prevents the opener disc's hub from being located on the outside of the opener disc, especially if it is a large heavy-duty hub (“outside” refers to the side away from the furrow being formed). Hence, a double-disc design has somewhat limited options as to where to locate relatively large hubs, since the opener discs must be at a narrow angle to each other to cut the soil properly, with such relationship physically precluding large hubs from being between the discs. On the single-disc design, the large hubs are typically located on the opposite side of the opener disc from the gauge wheel, which is the inside of the opener disc.
With a large hub on the inside of the opener disc, the seed delivery tube must pass either ahead of the hub or behind it. If the seed tube passes in front of the hub, the trajectory of the seeds passing inside the tube will be approximately at a 45-degree angle to the furrow (in the horizontal plane of the soil when on level terrain), aimed rearward as much as downward, due to the need for the seeds to enter the furrow when it has appreciable width, which would be directly below the hub and rearward of it. The rearward seed trajectory poses a significant problem of ricochet, which is the tendency of the seeds to bounce upward and out of the furrow after striking the soil or the opener disc after the seeds exit the seed-directing tube and/or boot. While a significant problem for grain drills with gravity-fed seed delivery, this problem is greatly exacerbated by forced-air delivery which has become commonplace on larger width drills called “air drills.” The seeds are carried in an air stream and move at a velocity greater than that attained by seeds falling solely under the influence of gravity, thereby increasing the ricochet effect. Further, if no provision is made for the pressure of the air stream to be vented or diffused to the ambient atmosphere until the seeds exit the lower end of the seed tube or boot, the air stream itself can carry lighter seeds out of the furrow as the air stream blasts into the furrow and then out of the furrow as it escapes.
A single-disc no-till drill opener design that has met with great success in the marketplace is typified by the John Deere drill models 1590 and 1890, and their predecessor models 1560 and 1860 (hereinafter “Deere 60- and 90-series”), both of which are slightly updated versions of the basic opener design described in U.S. Pat. No. 4,760,806 issued to Bigbee, which was first embodied in John Deere drill models 750 and 1850 (hereinafter “Deere 50-series”). On the Deere 60- and 90-series openers, as well as the 50-series, the seed boot is held directly on the opener subframe via a single bolt, with the boot being able to pivot on the bolt's axis by a few degrees. The boot is urged toward the opener disc by a leaf spring secured in a recess below the bolt, which continually holds one side of the boot's forward/lower edge flush against the opener disc. The seed tube passes forward of the disc's hub and enters the top of the boot near the aforementioned bolt attachment point which is also ahead of the hub. The seed tube is formed of steel pipe, being insertable inside a channel cast in the seed boot, with a threaded stud retaining bolt being located perpendicular to the axis of the tube and fitting into holes provisioned in the boot and tube. This stud bolt is difficult to align with the tube hole during (re)installation, and protrudes into the seed flow area inside the pipe, thereby becoming a primary cause of tube and boot plugging on the Deere 50-, 60-, and 90-series openers. Due to corrosion from moisture, and dust from seed treatments and prilled fertilizers passing inside the tube, these stud bolts often become extremely difficult to remove after a year or more. Further, because the various seed tubes on the various Deere 50-, 60-, and 90-series drill models all have bends along their length to circumnavigate the hub and other components, and/or to join the boot, the debris and obstructions which from time to time accumulate inside the tube are often difficult to dislodge. Arc curvature of the internal channel in the cast seed boot creates similar problems. Furthermore, the internal channel of the boot on these drill models is inclined about 45 degrees from vertical during field operation, which is far less conducive to seed and fertilizer flow than is a more vertical and less convoluted route into the soil. At the end of a seeding pass, or for transport, the opener assemblies are rotated (via a rockshaft torqued hydraulically) upward at the rear, which causes the internal channel of the seed boot to become more nearly horizontal yet. This generally results in fertilizer and/or seed settling into the boot channel and again adds propensity to clog the boot and tube, especially since both seed and fertilizer draw moisture from the air if the drill is parked overnight or during a rainy spell.
Other single-disc drill designs have routed the seed tube behind the opener disc's hub, resulting in the seed tube being more nearly vertical, and possibly angled slightly forward at the lower end. The more vertical orientation results in less seed ricochet, although it is quite important that the tube not be too far rearward in relation to the opener disc because of reduced control over seed placement, and it is also important that a boot and seed bounce flap adequately direct the seeds into the bottom of the furrow. This seed tube arrangement was integrated into a single-disc no-till opener that was marketed for several years (now discontinued) as Flexi-coil's “FSO” or “F/SO,” and is depicted in U.S. Pat. No. 6,237,696 B1 issued to Mayerle. The shape and location of the Mayerle '696 boot and tube allow much greater precision in placing seeds at the bottom of the seed furrow as compared to the Deere 60- and 90-series. The FSO model attached the boot (“scraper plate”) to the seed tube via two adjustable bolts that pinched a rubberized pad, with these components being oriented such that tightening a specific bolt would typically align the front edge of the boot against the opener disc. However, in field conditions, this configuration was generally more troublesome than the Deere 50-, 60-, and 90-series with their ‘automatic’ spring-loaded tension to constantly and continuously align the boot with the opener disc. On the FSO, the tube itself was attached directly to the opener subframe via two cap-screw studs, thus there was no provision for rapid removal of the tube in the field, nor in quickly separating the tube from the boot for clearing of obstructions in either.
Baugher et al., U.S. Pat. Nos. 5,595,130, 5,802,995, and 6,029,591, depict a single-disc opener with a tube passing rearward of the opener disc's hub, with the boot (“runner”) attached directly to the tube. The various seed tubes depicted in Baugher '130, '995, and '591 are fully integrated with and rigidly affixed to the “runner” or “shoe” (a.k.a. boot) depicted and described therein, with the entire boot and tube assembly being attached to the opener subframe at a forwardly located point. In all three Baugher patents, the entire boot and tube assembly pivots a few degrees along the axis of a single attaching bolt or pin at the forward end of the assembly, and is biased toward the opener disc with a spring device. In the '995 and '130 patents, the boot pivots about an axis that is mostly horizontal (with its axis along the direction of travel), while in the '591 patent it pivots about an axis that is nearly vertical. While the Baugher '130, '995, and '591 patents retain most of the other functional elements of the Deere 50-, 60-, and 90-series opener, the seed boots and tubes depicted therein involve substantial revision of the opener subframe design to accommodate the boot and tube; i.e., the boots and tubes depicted in these patents wouldn't fit existing Deere 50-, 60-, and 90-series openers, nor would any alterations allow the boots and tubes to fit those openers without a substantial rebuilding of the opener subframe. The Baugher '130, '995, and '591 patents also depict a seed tube which is still oriented somewhat rearward and not forward at its lower end, and also with the lower end of the tube located more rearward of the opener disc's axis than is desirable since the disc is useful in holding the soil and duff out of the furrow while seeds are being placed, and this occurs to the greatest extent where the opener disc is at the bottom of the furrow (i.e., directly below the disc axis).
Yet another type of seed boot for single-disc drill openers is described in Wendling et al., U.S. Pat. No. 6,347,594 B1, with a substantially vertical seed tube passing rearward of the opener disc's hub. The seed tube is attached rigidly to a narrow boot via two bolts, which again prevents rapid disassembly for inspection or maintenance. This tube and boot assembly attaches to the opener subframe via a bolt which allows the entire tube and boot assembly to pivot a few degrees on the bolt along a horizontal axis (approximately along the direction of travel, and parallel to the plane of the opener disc). The boot and tube assembly is biased toward the opener disc via a leaf spring.
There is a need for an improved seed tube mounting assembly for use with agricultural seeders.